As vehicles in which environmentally-friendly zero-emissions from cars are taken into consideration in society as well as governments, electric vehicles, petrol-electric hybrid vehicles, fuel-cell vehicles, and the like are the obvious answer in recent years. In each of these vehicles, an electric motor to generate a driving force and a battery to store power to be fed to the electric motor are mounted. On hybrid vehicles, internal combustion engines are mounted as driving force together with an electric motor, and on fuel-cell vehicles, fuel cells are mounted as direct current power supply for driving the vehicles.
Some of known vehicles with on-board, such vehicle-driving batteries are capable of charging the batteries directly from owner's home electrical power supplies. For example, power is supplied from a general household power supply to a battery through a charge cable connected between an outlet of a commercial power supply provided with a house and a charge port provided with a vehicle. The vehicle that is capable of charging an on-board battery directly from a power supply located outside the vehicle will be referred to as a “plug-in vehicle”.
The specifications of plug-in vehicles are specified, in the United States of America, as “SAE electric vehicle conductive charge coupler” (non-patent document 1), and specified, in Japan, as “General Requirements for Conductive Charging System for Electric Vehicles” (non-patent document 2).
In “SAE electric vehicle conductive charge coupler” and “General Requirements for Conductive Charging System for Electric Vehicles”, the specifications of a control pilot are specified as one example.
The control pilot is defined as a control line that connects between a control circuit of EVSE (Electric Vehicle Supply Equipment), which supplies power from wiring in facilities to vehicles, and a grounded portion of a vehicle via a control circuit of the vehicle, and a pilot signal transmitted via this control line is used as a basis on which to determine the connecting state of a charge cable, the propriety of an power supply from a power supply to a vehicle, the rated current of EVSE, and the like.